Air pump



FIG. 1 is a left side elevational view of an air pump showing my new design;

FIG. 2 is a front elevational view thereof, the rear view being a mirror image thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof. 

The ornamental design for an air pump, as shown and described. 